You return a value by using the standard ScriptEase API calls sePutNumber, sePutString, and so forth. The object/member pair to put to is SE_RETURN,SE_VALUE. See "SE_RETURN EXPLAINED" for a thorough discussion of using SE_RETURN. For the simple case, you just put a value to SE_RETURN,SE_VALUE. For instance, your wrapper function could return the number 10 via:
sePutNumber(se, SE_RETURN,SE_VALUE, 10);
If you return nothing, by default the undefined value is returned. For constructor functions, the pre-constructed object is returned in this case.